Axial area and anteroposterior diameter as estimates of left atrial size using computed tomography of the chest: Comparison with 3-dimensional volume
Received 28 May 2009; accepted 24 October 2009. published online 30 November 2009.
Background
Left atrial (LA) size has incremental value in risk stratification.
Objectives
We aimed to assess feasibility and reproducibility of 2 quick measures of LA size by chest CT (axial LA area and LA anteroposterior [AP] diameter) by using contrast-enhanced and CT scans.
Methods
We measured LA size in 100 contrast-enhanced 64-slice multidetector CT (MDCT) scans (randomly selected from the ROMICAT collective) by (1) axial LA area at the level of the left ventricular outflow tract and the mitral valve leaflets, (2) AP diameter in 3-chamber view, and (3) 3-dimensional (3D) LA volume by Simpson's methods. We assessed interobserver and intraobserver intraclass correlation coefficient (ICC) for axial LA area and AP diameter as well as their correlation to 3D LA volume. For axial area, feasibility and reproducibility were also determined in 100 non–contrast MDCT scans, randomly selected from the Framingham Heart Offspring collective.
Results
In contrast-enhanced CT, both LA axial area and AP diameter had excellent reproducibility (interobserver: axial area: ICC, 0.96, mean relative difference, 2.4% ± 7.4%; AP diameter: ICC, 0.91, 3.6% ± 7.2%; intraobserver: axial area: ICC, 0.99, 0.4% ± 5.2%; AP diameter: ICC, 0.94, 1.7% ± 5.5%). Correlations with 3D volume were better for axial area (r=0.88) than for AP diameter (r=0.67). In non–contrast images, axial area could be assessed with excellent reproducibility (interobserver: ICC, 0.96, 0.5% ± 8.3%; intraobserver: ICC, 0.99, 0.01% ± 4.4%).
Conclusion
Both AP diameter and axial LA area permit quick and reproducible estimates of LA volume in contrast-enhanced and non–contrast electrocardiographic-gated chest CT. However, LA area should be used preferably over AP diameter because of its better agreement to 3D LA volume.
aCardiac MR PET CT Program, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 165 Cambridge Street, Suite 400, Boston, MA 02114, USA
bCardiology Division, Massachusetts General Hospital, Harvard Medical School, 165 Cambridge Street, Suite 400, Boston, MA 02114, USA
cDepartment of Cardiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
dDivision of Endocrinology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
eFramingham Heart Study of the National Heart, Lung, and Blood Institute, Framingham, MA, USA
Corresponding author.
Conflict of interest: The authors report no conflicts of interest.
This work was supported by the National Heart, Lung, and Blood Institute's Framingham Heart Study (N01-HC-25195) and by the National Institutes of Health (NIH) (R01 HL080053). A.A.M. is supported by a grant from the German National Academic Foundation. Q.A.T. has received support from NIH (T32HL076136 and L30HL093896). C.L.S. is supported by grants from the Federal Ministry of Education and Research, and Foundation of German Business, Berlin.
ABSTRACT